During the next year, we plan to study chick, mouse, and rat retinal and tectal cell reaggregation, cell affinities, and synapse formation in cultures maintained in intracerebrally implanted capsules in chicks. We also plan to study: 1. Methods for maintaining ganglion cell viability and for promoting regeneration of optic nerve fibers following their lesion in quail. 2. The ability of optic nerve fibers in Xenopus to reach the tectum through abnormal pathways after experimental surgical diversion.